1. Field of the Invention
The present invention relates to an electronic component that reduces equivalent series resistance (ESR) while allowing for sufficient absorption of thermal stress and mechanical stress, and is optimum for multilayer capacitors used in a switching power supply.
2. Description of the Related Art
In recent years, due to advances in compactness and improvements in large current flow of the switching power supply, the necessity for diffusing and radiating heat that generates from components mounted upon this switching power supply has arisen. Consequently, an aluminum wiring board with great heat radiating capability is generally employed for this switching power supply. However, the thermal expansion coefficient for this aluminum wiring board is large.
Accordingly, due to directly mounting upon an aluminum wiring board a ceramic component with a thermal expansion coefficient greatly differing from that of this aluminum wiring board, cracks may develop in this component due to large thermal stress generating in this component, or the aluminum wiring board may greatly transform due to thermal expansion of the aluminum wiring board itself, whereby developing cracks in this component due to mechanical stress. As a result, there were fears that reliability of the switching power supply would be lost.
Meanwhile, a ceramic capacitor element with a long life span and excellent frequency characteristics is generally utilized as a smoothing capacitor for smoothing switching power supply output. Due to the above problems, however, in the case of mounting this capacitor element upon an aluminum wiring board, one that has a pair of metallic terminals connected to this capacitor element is generally used.
Specifically, a conventional compound ceramic capacitor 100 is illustrated in FIG. 14 and FIG. 15, whereby the compound ceramic capacitor 100 is described below based on these drawings.
The interior of this compound ceramic capacitor 100 has a structure where two types of T-shaped internal conductors 104 and 105 illustrated in FIG. 14 overlap via ceramic layers 103A. A multilayer body 103 illustrated in FIG. 15 is then formed by layering a plurality of these ceramic layers 103A, and these internal conductors 104 are extended toward one of the four side surfaces of this multilayer body 103. Furthermore, the internal conductors 105 are extended toward the side surface of the multilayer body 103 opposite to the side surface whereat the internal conductors 104 are extended.
Moreover, as shown in FIG. 15, terminal electrodes 106, which are to be connected to the internal conductors 104, and terminal electrodes 107, which are to be connected to the internal conductors 105, are respectively placed at mutually opposing side surfaces of multilayer capacitor elements 101. As illustrated in FIG. 15, a pair of metallic terminals 111, 112 that are respectively formed in an L-shape are then attached by solder or conductive adhesive in a form sandwiching two multilayer capacitor elements 101, for example. Thus, this pair of metallic terminals 111, 112 plays the role of absorbing and alleviating through elastic deformation the stress that generates due to thermal expansion and the like of the aluminum wiring board, and reducing the stress that generates in the ceramic multilayer capacitor elements 101.
At the same time, accompanying improvements in large current flow for the switching power supply, a large ripple current comes to flow within the smoothing capacitor. Since this ripple current is consumed in the form of heat generation due to the equivalent series resistance (ESR) of the capacitor, which then self-heats according to charging and discharging, detrimental effects to the life of the capacitor occur.
Accordingly, recent increase in ripple currents have come to threaten the reliability of the multilayer capacitor elements 101 regardless of using the aluminum wiring board with great heat radiating capability. The above compound ceramic capacitor 100 is then greatly influenced by the electric resistance of the metallic terminals 111 and 112, having defects that incur an increase in ESR.
Thus, even with a multilayer capacitor having a pair of metallic terminals as is used for the aluminum wiring board, reduction in ESR has come to be desired.
The present invention aims to provide an electronic component that reduces ESR while allowing for sufficient absorption of thermal stress and mechanical stress.
According to a first aspect of the present invention, an electronic component, comprising a dielectric element formed by layering dielectric layers; two types of internal conductors, which are respectively arranged within the dielectric element while separated from each other by the dielectric layers, and have a plurality of extended portions, respectively, that are extended toward a plurality of side surfaces of the dielectric element, respectively; two types of terminal electrodes, which are arranged at a plurality of side surfaces of the dielectric element, respectively; one of the two types of terminal electrodes connected to a plurality of extended portions of one of the two types of internal conductors, and the other of the two types of terminal electrodes connected to the remaining plurality of extended portions; and a pair of metallic terminals, which are respectively formed by metallic material; one of the metallic terminals connected to one of the two types of terminal electrodes, and the other of the metallic terminals connected to the remaining terminal electrodes, is provided.
According to such electronic component, operations as in the following take effect.
The electronic component according to this aspect has a structure with two types of internal conductors respectively arranged within a dielectric element, which is formed by layering dielectric layers, while separated from each other by the dielectric layers, and a plurality of extended portions, respectively, that are extended toward a plurality of side surfaces of the dielectric element, respectively, are provided to these two types of internal conductors, respectively.
Furthermore, two types of terminal electrodes are arranged at a plurality of sides surfaces of the dielectric element, respectively. One of these two types of terminal electrodes is connected to a plurality of extended portions of one of the two types of the internal conductors, and the other of these two types of terminal electrodes is connected to the remaining plurality of extended portions.
Moreover, a pair of metallic terminals are respectively formed by metallic material, of which one of the pair of metallic terminals is connected to one of the two types of terminal electrodes, and the other of the metallic terminals is connected to the remaining terminal electrodes.
Thus, according to this aspect, the elastic deformation of the metallic terminals assures absorption of the flexure and thermal expansion of the aluminum wiring board, thereby reducing thermal stress and mechanical stress that generate in the multilayer capacitor elements and stopping cracks from generating in the multilayer capacitor elements.
Furthermore, in this aspect as described above, the plurality of extended portions that are extended toward the plurality of side surfaces of the dielectric element, respectively, are provided to the two types of internal conductors, respectively, and the two types of terminal electrodes are arranged at a plurality of side surfaces of the dielectric element, respectively. Moreover, since it has a structure with these two types of internal conductors and two types of terminal electrodes connected to each other, the area of the portions connecting the internal conductors and terminal electrodes increases. Accordingly, the area of the portions connecting the terminal electrodes and metallic terminals then also increases, ultimately reducing ESR as a result.
Thus, since the area of these connecting portions increases and ESR reduces, according to this aspect, an electronic component that decreases ESR while allowing for sufficient absorption of stress can be obtained.
Furthermore, due to the increased area of each connecting portion, radiation to the aluminum wiring board is improved and self-heating is reduced, leading to improvements in reliability of the multilayer capacitor elements. On one hand, by decreasing ESR, elimination of high ripple currents can be achieved, as well as self-heating of the capacitor that generates due to charging and discharging is reduced, whereby increasing the life of electronic components such as capacitors is possible.
On the other hand, respectively forming a pair of metallic terminals in a form having a plurality of connecting surfaces whereto the terminal electrodes are connected, respectively, may be considered as a modified example of the electronic component according to this aspect. Thus, according to this modified example, since the pair of metallic terminals have a form that has a plurality of connecting surfaces, respectively, which are respectively connected to the terminal electrodes, the area of the portions connecting the terminal electrodes and metallic terminals can be increased by effectively utilizing the side surfaces of the dielectric element, and the operational effects of this aspect may be even more reliably provided.
Furthermore, each metallic terminal obtaining a plurality of connecting surfaces by folding a board material may be considered as a modified example of the electronic component according to this aspect. Thus, according to this modified example, merely by folding the board material, a plurality of connecting surfaces may be easily formed, allowing for the terminal electrodes to be connected at these plurality of connecting surfaces. Consequently, the area of the portions connecting the terminal electrodes and metallic terminals increases, and the operational effects of this aspect may be even more reliably provided even according to this modified example.
At the same time, one end portion of each metallic terminal is a connecting side that is connected to a terminal electrode, as well as the other end is an outer connecting portion that is connected to the outside may be considered as a modified example of the electronic component according to this aspect. Thus, according to this modified example, since the outer connecting portions are connected to, for example, land patterns of an external aluminum wiring board, the terminal electrodes and outer elements can be reliably connected via the metallic terminals. Thus, the operational effects of this aspect may be even more reliably provided even according to this modified example.
Furthermore, associated herewith, forming a plurality of outer connecting portions in the metallic terminals may be considered as a modified example. In other words, according to this modified example, since the outer connecting portions that are connected to the outside are formed in plurality, the area of the portions connecting the metallic terminals and the outside increases, whereby the operational effects of this aspect may be even more reliably provided even according to this modified example.
According to another aspect of the present invention, an electronic component, comprising a dielectric element formed by layering dielectric layers; two types of internal conductors, which are respectively arranged within the dielectric element while separated from each other by the dielectric layers, and have a single extended portion that is extended in a form continuing across a plurality of side surfaces of the dielectric element, respectively; two types of terminal electrodes, each of which is arranged in a form continuing across a plurality of side surfaces of the dielectric element; one of the two types of terminal electrodes connected to an extended portion of one of the two types of internal conductors, and the other of the two types of terminal electrodes connected to the remaining extended portion; and a pair of metallic terminals, which are respectively formed by metallic material; one of the metallic terminals connected to one of the two types of terminal electrodes, and the other of the metallic terminals connected to the remaining terminal electrode, is provided.
According to such electronic component, operations as in the following take effect.
The electronic component according to this aspect has the same structure as with the above first aspect of the present invention. However, instead of respectively having the plurality of extended portions that are extended toward a plurality of side surfaces of the dielectric element, respectively, the two types of internal conductors respectively have a single extended portion that is extended in a form continuing across a plurality of side surfaces of the dielectric element. Accordingly, two types of terminal electrodes, which are respectively connected to the extended portions, are arranged in a form continuing across a plurality of side surfaces of the dielectric element, respectively.
Accordingly, since not only are the extended portions formed in a form continuing across a plurality of side surfaces of the dielectric element, but the terminal electrodes are also formed in a form continuing across a plurality of side surfaces of the dielectric element, the number of terminal electrodes can effectively be reduced without reducing the area of connecting portions. Not only do the same operations as with the above first aspect of the present invention take effect as a result, but manufacturing costs of electronic components are lowered.
Meanwhile, besides considering the same structure as with the aforementioned first aspect, forming the extended portion having a length of at least ⅓ the length of the side surface of the dielectric element whereto the extended portion of each internal conductor is extended may be considered as a modified example of the electronic component according to this aspect. Thus, according to this modified example where extended portions are formed to be longer than conventional ones, effective utilization of the dielectric element side surfaces is possible, and the operational effects of the above first aspect of the present invention may be even more reliably provided.
According to yet another aspect of the present invention, an electronic component, comprising a dielectric element formed by layering dielectric layers; two types of internal conductors, which are respectively arranged within the dielectric element while separated from each other by the dielectric layers, and have a single extended portion, respectively, which is extended in a form continuing across three side surfaces of the dielectric element; two types of terminal electrodes, each of which is arranged in a form continuing across three side surfaces of the dielectric element; one of the two types of terminal electrodes connected to the extended portion of one of the two types of internal conductors, and the other of the two types of terminal electrodes connected to the remaining extended portion; and a pair of metallic terminals, which are respectively formed by metallic material, one of the metallic terminals connected to one of the two types of terminal electrodes, and the other of the metallic terminals connected to the remaining terminal electrode, is provided.
According to such electronic component, operations as in the following take effect.
The electronic component according to this aspect has the same structure as with the above first aspect of the present invention. However, instead of respectively having the plurality of extended portions that are extended toward a plurality of side surfaces of the dielectric element, respectively, the two types of internal conductors respectively have a single extended portion that is extended in a form continuing across three side surfaces of the dielectric element. Accordingly, two types of terminal electrodes, which are connected to the extended portions, respectively, are arranged in a form continuing across three side surfaces of the dielectric element, respectively.
Accordingly, not only do the same operations as with the above first aspect of the present invention take effect according to this aspect, but the extended portions are formed in a form continuing across three side surfaces of the dielectric element, as well as the terminal electrodes are arranged in a form continuing across three side surfaces of the dielectric element. Thus, the number of terminal electrodes can effectively be reduced without reducing the area of connecting portions, whereby manufacturing costs of electronic components are lowered as a result.
Meanwhile, the same structure as with the aforementioned first aspect of the present invention may be considered as a modified example of the electronic component according to this aspect.
According to yet another aspect of the present invention, an electronic component, comprising a dielectric element formed by layering dielectric layers; two types of internal conductors, which are respectively arranged within the dielectric element while separated from each other by the dielectric layers; one of the two types of internal conductors having a single extended portion that is extended in a form continuing across a plurality of side surfaces of the dielectric element, and the other of the two types of internal conductors having a single extended portion that is extended toward one side surface of the dielectric element; two types of terminal electrodes, at least one of the two types of terminal electrodes arranged in a form continuing across a plurality of side surfaces of the dielectric element; one of the two types of terminal electrodes connected to the extended portion of one of the two types of internal conductors, and the other of the two types of terminal electrodes connected to the remaining extended portion; and a pair of metallic terminals, which are respectively formed by metallic material; one of the metallic terminals connected to one of the two types of terminal electrodes, and the other of the metallic terminals connected to the remaining terminal electrode, is provided.
According to such electronic component, operations as in the following take effect.
The electronic component according to this aspect has the same structure as with the above first aspect of the present invention. However, instead of the two types of internal conductors that respectively have the plurality of extended portions, which are extended toward a plurality of side surfaces of the dielectric element, respectively, one of the two types of internal conductors have a single extended portion that is extended in a form continuing across a plurality of side surfaces of the dielectric element, and the other of the two types of internal conductors have a single extended portion that is extended toward one side surface of the dielectric element. Accordingly, at least one of the two types of terminal electrodes, which are respectively connected to the extended portion, is arranged in a form continuing across a plurality of side surfaces of the dielectric element.
Accordingly, not only do the same operations as with the above first aspect of the present invention take effect according to this aspect, but one of the two types of internal conductors has an extended portion that is formed in a form continuing across a plurality of side surfaces of the dielectric element, and at least one of the terminal electrodes is arranged in a form continuing across a plurality of side surfaces of the dielectric element. Thus, the number of terminal electrodes can effectively be reduced without reducing the area of connecting portions, whereby manufacturing costs of electronic components are lowered as a result.
Meanwhile, besides considering the same structure as with the aforementioned first aspect, connecting the terminal electrodes, which are formed continuously across a plurality of side surfaces of the dielectric element, to a single extended portion that is extended in a form continuing across a plurality of side surfaces of the dielectric element may be considered as a modified example of the electronic component according to this aspect. In other words, by connecting the above terminal electrodes across the entire individual extended portion, which is extended in a form continuing across a plurality of side surfaces, the operational effects of this aspect may be even more reliably provided.